DIY_EFI Digest Monday, December 6 1999 Volume 04 : Number 679 In this issue: Getting facts straight! (1/3) Getting facts straight! (2/3) Getting facts straight! (3/3) Mazda MX6 & Probe Turbo engines Subject: KLUTCH!!! Re: cycles re: Add-on systems which affect output pulse width? See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Mon, 6 Dec 1999 07:06:58 -0700 From: bearbvd@xxx.net (Greg Hermann) Subject: Getting facts straight! (1/3) #$%^&*() I hate digest mode. Sorry about the 2/2 coming through but the 1/2 being too big. Tried it first without dividing! #$%^&. the $#%^& list doesn't tell you when you post something too big, either!! $%^& Greg ><< Most engines need 15 to 20% more fuel than stoich to > make peak power and 10% less to make peak efficiency. >> > >and > ><> > >Three helpful tidbits and a bunch of complaining. If you need to unsubscribe >then > The flames are unnecessary and unproductive! Not needed if we would have a quasi-professional environment on this list! The facts are in the neighborhood, but not necessarily accurate, either! > >Hi Phil, > >I found Scotts comments quite good! > He was at least in the ball park. >>And just a hint to John. The limiting factor is your first choice of >>max pw >>at 12.8 and second 7000 rpm has a max pw of 7.57ms. > > >I'm not sure that I understand what you mean about limiting factor but an >engine >cycle is 720 degrees and therefore, at 7000RPM, with an 80% duty cycle the max >pw is 13.7ms. Correct numbers. By limiting my pulse width to less than 75% I just needed >slightly larger injectors. By using Lucas injectors, with a shorter open time, >I can use a short pulse width at idle and still keep the engine ticking over >smoothly. NOTE that, while what you have said is true, the Lucas injectors also give much poorer quality atomization of the fuel (than the presumed Bosch alternative). Poor atomization of the fuel has another entire set of disadvantages! (continued) Greg ------------------------------ Date: Mon, 6 Dec 1999 07:07:30 -0700 From: bearbvd@xxx.net (Greg Hermann) Subject: Getting facts straight! (2/3) (continued from 1/3) Another possible approach is to use staged injectors. Another, still more fascinating, approach is to use air atomization of the fuel delivered by the injectors--and thus get EVEN BETTER atomization of the fuel than is given by GOOD carbs. This approach would also let one get still wider dynamic range out of the injectors by allowing one to take the fuel rail pressure MUCH lower (at light loads) than what gives even minimally acceptable fuel atomization otherwise. > >BTW, theory finally caught up with real life after I discovered a software >glitch in the ignition timing that had my advance at 65 degrees at high RPM. >(oops). Now I (properly) limit advance on this engine to 34 degrees and >maximum >advance is in at 4000. VTEC solenoid comes on at 3700RPm and we are achieving >134HP at 6700RPM. Suddenly my Volumetric Efficiency table matches theory and >tuning the engine has become far more fun. Sweet! How much stuff did you melt/break?? With regard to mixture requirements for max power/max efficiency: With the superior fuel distribution that comes with port injection, it has been learned that not nearly so much enrichment (beyond stoich) is necessary to get to maximum power.13 or 13.5 , sometimes even 14 to 1 appears to be enough, at least with port injection. There are TWO effects which lead to maximum power happening with the mixture richer than stoich. 1.: The selective burning of the hydrogen component of the hydrocarbon fuel before the carbon component. The hydrogen component has a higher heat of combustion than the carbon, and therefore, for a limited amount of oxygen available, the combustion process can actually generate a bit more heat (and therefore power) by burning more hydrogen and wasting some carbon. 2. A cooling effect on the engine cycle. SOME of this effect is brought about by the adiabatic cooling of the inlet charge by the latent heat of evaporation of the fuel--this effect makes for a denser charge, thus more net oxygen and fuel to be burned passing through the engine and more power. BUT--contrary to popular mythology, this is NOT the primary effect! The charge can only be cooled SO much before it is saturated with respect to fuel vapor, and that is IT! There is MORE than enough fuel present, even in just a stoich mixture, to cool the inlet charge o a saturated condition!! The heat energy necessary to evaporate all of the fuel (barring hot spots in the manifold, or spraying fuel on the back side of closed, hot intake valves (exactly as is done in MANY port injected engines) does not become AVAILABLE (emphasis because this word is used in its context as the correct thermodynamic term) until the intake valve closes and the compression stroke starts! Absorbtion of the latent heat of vaporization of the fuel by the charge during the compression stroke makes the compression part of the cycle move from being an adiabatic process closer toward being an isothermal process--which means several things: isothermal compression requires less negative power, increasing the net output of the engine; the peak temperature and pressure at the top of the compression stroke are significantly lower, one can go to a higher effective compression ratio because of the reduction in the tendency to detonate and/or pre-ignite (with the lower T/P conditions), and, because the TP conditions at ignition are lower, the peak cycle temperatures, cycle efficiency, and positive power stroke output are ALL lower. BUT--the net effect on engine output is about 2% positive, if the compression ratio remains constant. If the higher possible compression is USED, then output goes up more, as usual. Lots of folks don't realize it, but an alky (methanol) fueled engine, even with a 13 to 1 compression ratio, does not have enough heat/work available to vaporize ALL of the fuel, even by the time ignition occurs. The mixture is still partially WET at TDC on the compression stroke in an alky fueled engine!! The first part of the combustion heat must therefore be wasted to finish evaporating the fuel--which is precisely why alky engines can be rather hard to light and like to foul their plugs, particularly when they are cold. And is also why they are not particularly fuel efficient. (cont'd.) Greg ------------------------------ Date: Mon, 6 Dec 1999 07:07:51 -0700 From: bearbvd@xxx.net (Greg Hermann) Subject: Getting facts straight! (3/3) >(continued from 2/3) > >I have no hard numbers to back up this contention, YET, but I suspect that >if a port injected engine had MUCH BETTER fuel atomization than is >attainable with current art injectors, and a much quicker fuel squirt--one >timed with the high velocity flow of air in the port--that it would not >only make more power AND have a lower BSFC at WOT conditions, but would >ALSO want a mixture somewhat RICHER of stoich for maximum power than is the >case with current art port injected engines! WHY?? evaporatin fuel on the >back side of a hot intake valve allows fuel vapor to displace air--reducing >output, whereas--getting finely atomized fuel into the cylinder, and not >vaporizing much of it 'til after the I valve has closed not only avoids >displacement of inlet air by fuel vapor, but takes full advantage of the >heat absorbtion effect (as detailed above) during the compression stroke. >- ------------------------------------------ > >As to the best ECONOMY mixture--going lean of stoich tends to insure >burning every last bit of the fuel, and thus improves economy. The limit is >usually when one approaches a lean misfire condition. (Misfires waste >fuel.) Better fuel atomization and distribution BOTH work to push this >limit further out. Also--the basic Otto cycle efficiency, even at WOT, >improves with a leaner mixture. Good chamber geometry and good mixture >turbulence during combustion push the lean limit further out, as well as >allowing better efficiency through higher compression ratio (by avoiding >pre-ignition and/or detonation). Furthermore-- leaner mixtures at part >throttle (with a spark ignition engine) reduce pumping losses, improving >economy even further at part throttle. SO--how far lean of stoich is best >for economy--the answer is--"As far as you can get away with!"--not some >set rule! It all depends on a large number of engine design factors. > >So--what are we left with that is magical about stoich? The facts that a >stoich mixture is the point where a three way catalyst works best for >cleaning up tailpipe emissions and that it is also the point where a >standard EGO or HEGO exhaust oxygen sensor (as opposed to a UEGO WBO2 >sensor) switches its output. Period. > >In closing--I would like to say that this list will return to far better >health once it finally get put onto a different server, and can FINALLY get >off of the #$%^^&^*& digest mode--too many of the really knowlegeable >people here have been driven into the lurk mode by the digest format! > >AND--the trick to getting good information off of the internet is the same >as it is anywhere else in life--one has to learn to sort useful information >out from BS!! There are always plenty of people in any field who are >willing to spread BS indiscriminately, usually without knowing any better, >but sometimes with premeditation and for profit! Good, old fashioned >fundamental education taken together with the ability and experience with >applying it is one of the most effective tools for accomplishing this >sorting process! > >Unfortunately, high performance engines seem to attract more than their >proportionate share of the BS and the profiteers (particularly the ones who >feed on ignorance)! > >Although I am NOT going to be so bold as to say where, I WILL promise that >there is a bunch of good information in this last series of posts--it's up >to all of you to figure out where! > >Back to lurk mode, at least 'til we are off digest mode! > >Regards, Greg > >------------------------------ > >Date: Mon, 6 Dec 1999 10:01:24 +0800 >From: dzorde@xxx.com >Subject: Re: Signal of AMC 16 > >Mike, I had a similar problem trying to interface my Chev HEI to the >aftermarket >ECU, made the car undrivable as it saw multiple crossovers of the same trigger. >Try something along the lines of. > > 0.1uF 1k >coil ------||------/\/\/\/\/---------|--------------ECU > < > > 1k > > > | > ---- 15V zener diode >5W > /\ > | > gnd >regards > >Dan dzorde@xxx.com > > > > >Date: Sun, 5 Dec 1999 00:56:23 -0500 (EST) >From: Mike Comai >Subject: Ref. Signal off of AMC I6 > >I am currently trying to get my first major retrofit up and running. I >have everything installed and when I try to start it the injector's don't >fire. I was told that I need a filter on the negative side of the coil >and to feed the filtered signal into the Reference line on the ECM (which >I am using a '747). I was given a design for a filter which looks like >this: > >------------------------------ > >Date: Mon, 6 Dec 1999 10:14:04 +0800 >From: dzorde@xxx.com >Subject: Re: DIY_EFI Digest V4 #672 > >I'm doing this on my current s/c set-up (although car is not yet driveable), >anyway a blow off valve just venting of the air during idle and light cruise. >Put your foot down, the valve shuts and there is instant 17psi boost. Unlike a >turbo, you don't get a pop when it opens, but more of a constant whistle as it >lets a lot of air out unless wot. > >Due to the extremely hot air (currently don't have an intercooler yet) I'm >reluctant to recirculate it through the intake filter (but due to the very loud >whistle created by all this air veing vented in the engine bay I need to do >something). Can anyone see a problem with feeding the air from the blow off >valve into the exhaust system before the muffler and quieten it down this way. >The line could be fed in at 45deg angle with the exhaust flow. > >Dan dzorde@xxx.com > > >Date: Thu, 2 Dec 1999 19:02:36 -0500 >From: "Jonathan Davis" >Subject: Re: KLUTCH!!! > >Another way to do this, perhaps would be a large bypass valve that >recirculates >any boost until WOT. Something like that would be intoxicating to drive - >nice >fat kick in the pants at WOT... > >------------------------------ > >Date: Mon, 06 Dec 1999 02:19:16 -0500 >From: Chris Conlon >Subject: re: Add-on systems which affect output pulse width? > >"Andrew Brownsword" wrote: > >> It seems to me that this could be problematic if the ECU was designed to >>expect a particular voltage range and the stock airflow meter generated that >>full range ... in other words there is no buffer for going beyond the >>expected range of values. This seems fairly reasonable for an N/A engine >>since it is extremely unlikely that the car will have to deal with >1 >>atmosphere. > >I'm not going to get into this, really. You may very well run >into problems, especially with ignition timing, when you try to >trick an NA ECU into running much boost. (If you aren't >reprogramming it, that is.) > >> The alternative is to modify the ECU's output, which is a time dependant >>pulse width. It simply isn't possible to have full remapping control over >>the output because by the time you know what the pulse width is, the time at >>which you have to send it to the injectors has passed. It occurred to me > >You can get very close, though, and very easily, in at least a >couple different ways. This presumes you're running injectors a >good bit larger than stock and will not need to lengthen the >pulse. Take your basic HC11. Wire a switch (power mosfet most >likely) in series with each injector drive circuit, watch for >voltage drops, ground ref, etc. Control each switch via output >compare line. Also wire up input compare lines so they can >detect when the ECU is *trying* to fire the injector, >independent of your switch's position. (If you have more than >4 independent injector drive circuits, see 68332 instead.) Now >you can easily read RPM and load, more or less, via input >compares. You have a map, and for each rpm/pulse width point, >look up a new pulse width. (Or just multiply by old injector >size / new injector size, correct for short PW, etc etc.) >Leave each output compare line (switches) on, until the ecu >fires that circuit. You'll get an interrupt and time count >via input compare. Calculate how long you want the pulse to >be, program output compare to turn off at that time. When IC >turns off again, take another interrupt, turn OC back on. > >You can update RPM and desired-PW info at each injector firing >if desired. It is "behind reality" but not by much. Issues >exist with p&h drivers, need a dummy load, etc, or just supply >your own drivers. (Assorted details omitted, none too tricky.) > >I already have to do this (and more besides) for my semi >insane supercharged MR2 project, ugh. Lucky for me the ECU >already understands boost, timing retard, knock sensing, >etc, it just needs a few white lies about airflow & injector >sizes. > > >Now I had some questions for you, since you seem to know >Ford/Mazda stuff well. I did some searching for answers >but got confused and set it aside. I'd like to get an >MX-3 v6, and do some engine swapping. I've heard that a >2.5l v6 from the MX-6 (or 626?) will basically drop in. >Wasn't there a 2.5l *turbo* Ford Probe GT engine at one >point? If so would it drop in w/o much work? Basically I >think the MX-3 is cute and would get one if I knew I could >grab a decent turbo engine (well, a whole front cut) from >something and drop it in pretty easily. (Ignoring ECU hassles >of course, got to have some fun!) I know there are aftermarket >turbo kits, etc, but I was hoping for a factory turbo motor. >Am I just real wrong or was there such a beast? I'm pretty >sure there was a not-common MX-6 turbo... comments? Thoughts? > > TIA, > Chris C. > >------------------------------ > >End of DIY_EFI Digest V4 #678 >***************************** > >To subscribe to DIY_EFI-Digest, send the command: > > subscribe diy_efi-digest > >in the body of a message to "Majordomo@xxx. > >A non-digest (direct mail) version of this list is also available; to >subscribe to that instead, replace "diy_efi-digest" in the command > above with "diy_efi". ------------------------------ Date: Mon, 6 Dec 1999 09:13:37 EST From: ECMnut@xxx.com Subject: Mazda MX6 & Probe Turbo engines Chris, the same 2.2 Turbo 4cyl was offered in the Probe & MX6 from 1989-1992. I service PCs at a place called Midwest Engine, in Cleveland, OH.. The last time there, I saw one of those engines on a pallet. 800-234-1423. They are a good bunch of guys. Tell them I sent you, and you'll get the "oil burner special" 8-).... LOL Just kidding.. They have thousands of Japanese engines..What they don't stock, they can get pretty quickly,, Mike V > Now I had some questions for you, since you seem to know > Ford/Mazda stuff well. I did some searching for answers > but got confused and set it aside. I'd like to get an > MX-3 v6, and do some engine swapping. I've heard that a > 2.5l v6 from the MX-6 (or 626?) will basically drop in. > Wasn't there a 2.5l *turbo* Ford Probe GT engine at one > point? If so would it drop in w/o much work? Basically I > think the MX-3 is cute and would get one if I knew I could > grab a decent turbo engine (well, a whole front cut) from > something and drop it in pretty easily. (Ignoring ECU hassles > of course, got to have some fun!) I know there are aftermarket > turbo kits, etc, but I was hoping for a factory turbo motor. > Am I just real wrong or was there such a beast? I'm pretty > sure there was a not-common MX-6 turbo... comments? Thoughts? > > TIA, > Chris C. ------------------------------ Date: Mon, 6 Dec 1999 09:23:17 -0500 From: jacobss914@xxx.com Subject: Subject: KLUTCH!!! Subject: KLUTCH!!! > > Could one use an AC clutch to engage and disengage > the impeller. At idle and > > cruise, the impeller doesn't turn, but for gettin' > giggy, fire up the > > "blower" and blow past the NIGHT RIDER!!!!! > > > > Can an AC clutch "hold together" when attached to > a blower??? I am a little late onto this thread, but why not us a unit from an Supercharged MR2????? These little pieces had a elcro-clutch, so when you had to use crap gas, the engine could survive. Just a thought... Stephen Jacobs ------------------------------ Date: Tue, 07 Dec 1999 03:12:56 +1100 From: Phil Lamovie Subject: Re: cycles Hi John et al, ...but an engine cycle is 720 degrees and therefore, at 7000RPM, with an 80% duty cycle the max pw is 13.7ms. Yes John your quite right a 4 stroke IC engine has a working cycle that encompasses 720 degrees of crank. On the other hand an Injector is not any IC engine and has a duty cycle that is of one revolution only. This does of course give rise to the question... are you only injecting every second revolution of the engine ? If so that may establish part of the reason for the stumble you are experiencing. Phil ------------------------------ Date: Mon, 06 Dec 1999 08:15:55 -0800 From: "Andrew Brownsword" Subject: re: Add-on systems which affect output pulse width? > I'm not going to get into this, really. You may very well run > into problems, especially with ignition timing, when you try to > trick an NA ECU into running much boost. (If you aren't > reprogramming it, that is.) Others who have gone to forced induction on this engine haven't had problems with this, at least at the boost levels I'm looking at (6-7 psi). > Now I had some questions for you, since you seem to know > Ford/Mazda stuff well. I did some searching for answers > but got confused and set it aside. I'd like to get an > MX-3 v6, and do some engine swapping. I've heard that a > 2.5l v6 from the MX-6 (or 626?) will basically drop in. > Wasn't there a 2.5l *turbo* Ford Probe GT engine at one > point? If so would it drop in w/o much work? Basically I > think the MX-3 is cute and would get one if I knew I could > grab a decent turbo engine (well, a whole front cut) from > something and drop it in pretty easily. (Ignoring ECU hassles > of course, got to have some fun!) I know there are aftermarket > turbo kits, etc, but I was hoping for a factory turbo motor. > Am I just real wrong or was there such a beast? I'm pretty > sure there was a not-common MX-6 turbo... comments? Thoughts? There is a fellow in eastern Canada who dropped a 2.5L into the MX-3 successfully. There were some issues, but I'm pretty sure he sorted them out okay. You've got 2 choices for the 2.5L... the KL03 from a North American PGT or MX-6 (164 hp), or the KLZE (200 hp) from a Japanese car. The differences are in the intake manifold and compression ratio. There was no turbocharged version of this engine, but many people have done this (like me, for example). The MX-3's engine bay is smaller, however, and that might pose serious problems to mounting a turbo. Supercharging might be better. If you want to talk to a bunch of guys who know their stuff, checkout the mailing list... http://www.amber.org/mailman/listinfo/probe-perf The KL is a lovely, smoothly revving V6. You might consider that a KLZE tweaked out but not forced induction would be plenty in the MX-3 which is fairly light. Cheers, Andrew ------------------------------ End of DIY_EFI Digest V4 #679 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. A non-digest (direct mail) version of this list is also available; to subscribe to that instead, replace "diy_efi-digest" in the command above with "diy_efi".